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The original link⭐MybatisPlus learning notes ⭐ (3) To achieve logical deletion, paging

Look at the MybatisPlus module for this link

1. Logical deletion

Description:

Only for auto-injected SQL:

  • Insert: No restrictions
  • Lookup: Append the WHERE condition to filter out the deleted data, and the WHERE condition generated using wrapper.entity ignores this field
  • Update: Append where condition to prevent update to deleted data, and where condition generated using wrapper.entity ignores this field
  • Delete: Convert to update

Such as:

  • Delete: update user set deleted=1 where ID =1 and deleted=0
  • Search: select ID,name,deleted from user where deleted=0

Field types are supported:

  • Support all data types (recommended Integer, Boolean, LocalDateTime)
  • If the database field uses datetime, the logical undeleted value and the deleted value can be configured as a string null, and the other value can be configured as a function to get the value such as now()

Appendix:

  • Logical deletion is a solution to facilitate data recovery, protect the value of the data itself, etc., but it is actually deletion.
  • If you need to check frequently you should not use logical delete, but instead represent it as a state.

==1. Add field deleted== to the database and the corresponding entity class

Add @ to the entity class fieldTableLogicannotations

== make sure to set value and delval, otherwise the following error will be reported. I have been looking for more than an hour for the error ==

==2. Configure the configuration file

Mybtis-plus.global-config.db-config.logic-delete-value =1# Logical deleted value (default is1)
mybatis-plus.global-config.db-config.logic-not-delete-value=0# Logical undeleted value (default is0)
Copy the code

= = = = test

As you can see, the actual SQL being executed is the Update statement, which is the logical delete

2, the realization of paging query

Refer to official documents

1, create a configuration class, add paging plug-in == ==2

You can see that the query results are 8 and 9, because 7 has been logically deleted




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